This invention relates to a needle electrode and to a method of assembly thereof.
Needle electrodes have become important in the medical field, for example, to enable the detection of electrical activity in muscle fibers. Such needle electrodes can be used in conjunction with neurophysical recording systems to record and thereby diagnose a wide range of muscular and neurological disorders, and are particularly useful if provided in disposable form and to this end are usually provided with a sheath which is removed before use. The used needle electrode is discarded.
A prior art method of making a needle electrode is described in some detail hereinafter. The prior art method entails some problems. One such problem is that the prior art method includes the step of threading or pushing a needle wire through a cannula, which is an inherently difficult and hence a lengthy, time-consuming and expensive operation. What is worse, when the needle wire has been provided with an insulating coating, this coating can be scraped off by the mere action of pushing the needle wire through the cannula, resulting in short-circuiting the needle electrode during its manufacture and rendering it scrap, unfit for use.
The present invention overcomes and avoids the foregoing problems of the prior art needle electrode, and also overcomes the problems of the prior art method of making the prior art needle electrode.
It is accordingly an important object of the present invention to provide a needle electrode of increased reliability relative to the prior art needle electrode.
It is another object of the invention to provide a needle electrode of decreased cost relative to the prior art needle electrode.
It is a further object of the invention to provide a method of making a needle electrode that is faster and less expensive than the prior art method.
It is an additional object of the invention to provide a method of making a needle electrode that is more reliable in use than the prior art needle electrode.
A patentability search on the disclosure of the present invention has identified the following U.S. Pat. Nos.:
4,317,458 Yokoyama PA1 4,408,610 Sarnoff PA1 4,805,625 Wyler PA1 4,892,625 Prass
The search was extended to cover foreign art without uncovering any foreign references more pertinent than the above-identified U.S. patents.
Yokoyama addresses an electrode apparatus for cardiac pacing suitable for use in emergency circumstances. Sarnoff also presents an electrode suitable for emergency circumstances. Ritter teaches electrodes which are particularly useful as temporary heart pacer electrodes for cardiac stimulation during and after surgical procedures. Wyler introduces a sphenoidal electrode and insertion method. Prass envisages a handheld instrument for electrically stimulating exposed, subcutaneous tissue of a living body.
Further comments on the above-identified prior art patents follow;
Yokoyama and Wyler are concerned with surgical techniques involving the insertion of a needle and a sheath into tissue and withdrawing the sheath after the needle has become embedded in the tissue. There is relative movement of the sheath and the needle but the relative movement occurs only during use of the device.
Sarnoff discloses a conventional hypodermic needle arranged within a closed housing to maintain the needle sterile.
Ritter is concerned with a design of needle and pin which can be easily separated by being pulled apart.
Prass is not really concerned with a needle, but rather with a probe with a planar tip to facilitate making electrical contact. Moreover, the method of construction involves the use of a heat-shrinkable sleeve 54 around portions of a tube 50 and a male connector 40.
These references bear little or no significance to the present invention and do not anticipate the present invention in either its article aspect or its method aspect. Furthermore, no fair combination of any of these references with each other or with the prior art needle electrode disclosed herein or with the prior art method disclosed herein appears to render the present invention obvious.
The manner in which the present invention attains the foregoing objects and advantages will appear more clearly hereafter.